Figure 5-22.Floor plan of a typical bathroom.fitting) that leads to a 4-inch main house drain. Thevent pipe runs parallel to the floor drain, slightlyabove the lavatory.Figure 5-21, view B, is an isometric drawing ofthe water pipes, one for cold water and the other forhot water. These pipes are connected to service pipesin the wall near the soil stack, and they run parallel tothe drain and vent pipes. Look back at figure 5-20 andyou can see that the water service pipes are locatedabove the drain pipe.Figure 5-23 shows you how to read the designa-tions for plumbing fittings. Each opening in a fittingis identified with a letter. For example, the fitting atthe right end of the middle row shows a cross reducedon one end of the run and on one outlet. On crossesand elbows, you always read the largest opening firstand then follow the alphabetical order. So, if the fittinghas openings sized 2 x 1/2 by 1 1/2 by 2 1/2 by 1 1/2inches, you should read them in this order: A = 2 l/2,B = 1 1/2, C = 2 1/2, and D = 1 1/2 inches.On tees, 45-degree Y-bends or laterals, anddouble-branch elbows, you always read the size of thelargest opening of the run first, the opposite openingof the run second, and the outlet last. For example,look at the tee in the upper right corner of figure 5-23and assume it is sized 3 by 2 by 2 inches. You wouldread the openings as A = 3, B = 2, and C = 2 inches.Figure 5-23.How to read fittings.5-17